#!/usr/bin/ python3.8
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import itertools
from collections import deque

W, H = map(int, readline().split())
C = tuple(map(int, read().split()))


dx = (1, 0, -1, 0)
dy = (0, 1, 0, -1)

N = H * W
graph = [[] for _ in range(4 * N + 2)]
for i in range(N):
    x, y = divmod(i, W)
    for j, k in itertools.product(range(4), repeat=2):
        x1 = x - dx[j]
        y1 = y - dy[j]
        x2 = x + dx[k]
        y2 = y + dy[k]
        if not ((0 <= x1 < H) and (0 <= y1 < W)):
            continue
        if not ((0 <= x2 < H) and (0 <= y2 < W)):
            continue
        i1 = x1 * W + y1
        i2 = x2 * W + y2
        n = C[i]
        n1 = C[i1]
        n2 = C[i2]
        if n1 == n2:
            continue
        if (n1 <= n <= n2) or (n1 >= n >= n2):
            continue
        v = 4 * i1 + j
        w = 4 * i + k
        graph[v].append(w)
start = 4 * N
goal = 4 * N + 1
graph[start] = [0, 1]
graph[4 * (W * (H - 1) - 1)].append(goal)
graph[4 * (H * W - 2) + 1].append(goal)

INF = 4 * N + 100
dist = [INF] * (4 * N + 2)
dist[start] = 0
q = deque([start])
while q:
    v = q.popleft()
    dv = dist[v]
    dw = dv + 1
    for w in graph[v]:
        if dist[w] <= dw:
            continue
        dist[w] = dw
        q.append(w)

answer = dist[goal] - 1
if answer > 4 * N + 2:
    answer = -1
print(answer)